Many controllers are known, designed to be connected to a computer or digital device, which make it possible to generate sounds by pressing their keys, which by electric signals are interpreted by said digital devices via the corresponding audio circuit to emit that particular sound.
These types of controllers have a configuration similar to a traditional musical instrument, such as a piano keyboard, a guitar, wind instruments, etc, so that, although they can be used to digitally generate sounds of multiple musical instruments, it is typical that they are only used to reproduce the sounds of the musical instrument to which their external configuration corresponds.
In this regard, to use said controllers it is necessary to have musical knowledge as well as knowledge of the particular instrument for their use.
Although devices exist that offer an interface by way of a staff, they do not allow, by simply pressing one key at a time, production of the twelve chromatic notes in all possible tonalities, but they have a complex structure, whereby it is necessary to press several keys at the same time to obtain altered notes. This makes it impossible to play chords in real time.